Today many enterprises now use cloud-based computing platforms that allow services and data to be accessed over the Internet (or via other networks). Infrastructure providers of these cloud-based computing platforms offer network-based processing systems that often support multiple enterprises (or tenants) using common computer hardware and data storage. This “cloud” computing model allows applications to be provided over a platform “as a service” supplied by the infrastructure provider.
High availability (HA) database architectures prevent downtime and data loss by using redundant systems and software to eliminate single points of failure. Administrator error, data corruption caused by system or software faults, or complete site failure can impact the availability of a database. The only way to prevent being impacted by single points of failure is to have a completely independent copy of a production database already running on a different system and ideally deployed at a second location, which can be quickly accessed if the production database becomes unavailable for any reason.
Oracle Data Guard forms an extension to the Oracle relational database management system (RDBMS). In Oracle's Data Guard system, a database operates in one of the following mutually exclusive roles: primary or standby. Oracle Data Guard technology can help eliminate single points of failure, and prevents data loss and downtime in a simple yet economical manner by maintaining a synchronized physical replica of a production or primary database at a remote location. Oracle Data Guard maintains these standby databases as copies of the production database. Then, if the production database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage.
Data Guard enables a database administrator to change these roles dynamically by issuing the SQL statements, or by using either of the Data Guard broker's interfaces. One limitation of Data Guard technology is that it does not guarantee the automatic provisioning of a new standby database after a role change when primary database is not available due to various types of failures, such as hardware failures on the primary database server or storage sub-system.